Lubricating oil



Patented Feb. 13, 1951 LUBRICATIN G OIL John Mann Butler, Dayton, Ohio, assignor to Monsanto Chemical Company, St. Louis, Mo., a corporation of Delaware No Drawing. Application October 23, 1948,

' Serial No. 56,268

1 Claim. 1

This invention relates to the improvements of lubricating oils, and more particularly to the reduction of pour points of wax containing mineral oils. More specifically the invention relates to a method of altering the crystallization characteristics of the paraflin wax dissolved in lubricating oils, and avoiding the solidification of the lubricant upon cooling.

Many of the commercially available petroleum stocks contain high molecular weight hydrocarbon waxes, and the lubricating oil fractions separated by various refining procedures, contain a substantial proportion dissolved therein. Upon cooling these lubricants, the dissolved waxes crystallize in such form that the mass is solidified. It is known that some substances affect the crystallization of the wax and permit the lubricants to retain their fluidity after cooling to temperatures below the normal pour points of the oils.

The purpose of this invention is to provide a convenient and readily available agent for depressing the pour points of lubricating oils. A further purpose of this invention is to enable the selection of an effective pour point depressant for a wide variety of wax containing lubricating oils.

The pour points of lubricating oils are measured by a standard A. S. T. M. procedure, by which a sample of oil is heated and then gradually cooled while observing the fluid characteristics of the sample at every 5 F. interval, the temperatures being multiples of 5 F. The pour point is the lowest recorded temperature at which the sample is fluid. The details of the method of determining pour points are set forth in the American Society for Testing Materials publication, A. S. T. M. Standards on Petroleum Products and Lubricants (1946), p. 93, A. S. T. M. designation: D9739.

It has been discovered that there is a critical relationship between the length of the carboxylic acid group of allyl carboxylates and the pour point of a wax containing oil in which a polymer of the allyl carboxylate is an effective pour point depressant. Polymers of the allyl carboxylates, having allkyl chains longer or shorter than the critical length, may be less effective, or entirely ineffective in depressing the pour points of the same oil. In accordance with the invention the polymers of allyl palmitate are used as pour point depressants for wax containing oils having pour points between 40 F. and 70 F. Other polymeric allyl carboxylates are not effective pour point depressants for 40 F. to 70 F. pour oils, and

polyallyl palmitate is not efiective in higher or lower pour oils.

In the practice of this invention the polyallyl palmitate is prepared by the polymerization of allyl palmitate by heating in the presence of,

peroxy catalysts, such as benzoyl peroxide. The effectiveness of the polymer as a pour point depressant is not materially affected by the molecular weight of the polymer; the wide range of molecular weights achieved by conventional polymerization operations all appear to have the same or very similar pour point depression. The polymerized allyl palmitate may be used in an amount varying from 0.01 to 5 percent by weight, but the preferred operation involves the use of from 0.05 to 2 percent. The polymer is dissolved or dispersed in the lubricating oil by adding it directly and stirring the mixture until a homogeneous mixture or solution is efiected. It is frequently desirable to prepare master batches by dispersing or dissolving large amounts of the polyallyl palmitate in a lubricating stock, and thereafter mixing the concentrate with a suitable larger quantity of untreated oil, the proportions being achieved so as to have a small but effective proportion of the polyallyl palmitate in the final lubricant.

The invention may be practiced by using mixtures of polymeric allyl carboxylates containing predominantly polymeric allyl palmitate, and copolymers of mixed allyl carboxylates containing predominantly allyl p almitate and substantial proportions of near homologues, for example, allyLmyristate and allyl ste arate. These copolymers are generally derived from allyl esters of the mixed. fatty acids as obtained from animal and vegetable oils by saponification.

The pour point repressants described in this specification may be used in combination with other known depressants and with other modifying agents, such as viscosity index improvers, anti-oxidants and detergents.

The critical characteristics of the pour point depression of lubricating oils with polyallyl palmitate are demonstrated by the following specific examples.

Example 1 The critical effect of the length of the carboxylate chain of various polymerized allyl carboxylates was demonstrated by preparing one percent by weight solutions of polymerized allyl myristate, polymerized allyl palmitate and polymerized allyl stearate in a wax containing lubricating oil having a F. pour point. The three samples were tested by means of the standard A. S. T. M. measuring method and the observed data is set forth in the following table.

Pour Polymer of- Poji t, gfif g Allyl Myristate 30 +30 Allyl Palmitate 20 +40 Allyl Stearate 65 This demonstrates that the polyallyl stearate has no pour point depression, but in fact causes an increase in the pour point of the oil. The

. data demonstrates that polyallyl palmltate has 1 an efiective pour point depression action and that polyallyl myristate has only a moderate pour point depression action in the same 60 F. pour oil.

Example 2 g Final Pour, Depres- Point 0 F. sion, F.

The above table of measurements demonstrates 4 that polyallyl palmitate is not a pour point depressant for 20 pour oil, but that it is an effective pour point depressant for oils having pour points of and F. Polyallyl palmitate is also eflective in depressing the pour points of oils with pour points in excess of 60 F., for example F., but these oils are of little commercial importance. Similarly, polymers of allyl palmitate are also effective in depressing the pour points of oils having original pour points of less than 45 F., for example 40 F.

The invention is defined by the following claim.

I claim:

A lubricating composition which comprises a paraflin wax containing hydrocarbon lubricating oil having a pour point of 40 to 70 F., containing intimately dispersed therein from 0.05 to 2 percent by weight of polyallyl palmitate.

JOHN MANN BUTLER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,020,714 Wulfi et a1 Nov. 12, 1935 2,374,081 Dean Apr. 17, 1945 2,441,023 Larson et al. May 4, 1948 FOREIGN PATENTS Number Country Date 484,964 Great Britain May 12, 1938 OTHER REFERENCES Modern Methods of Refining Lubricating Oils, by Kalichevsky, Reinhold Publishing 00., 1938, page 183. 

